I have a 350 installed in my 37 p/u. Truck overheats after about 10-15 minutes of run time. 180 degrees climbing to over 200, regardless of outside temp. I have adjusted timing, replaced radiator cap. Fan is close to the radiator, but no shroud. I have checked all hoses, thermostat, etc. My question, add an electric pusher fan, shroud or replace the radiator?